800600 - canPlayType("video/mp4") == canPlayType("ViDeO/mP4") is true on OS X (case-insensitive) but false on Windows (case-sensitive)

Status: RESOLVED FIXED

(Core :: Audio/Video: Playback, defect, P2)

Description

[Chris Peterson [:cpeterson]]

Attachment: canPlayType.html

1. Chrome and Safari's canPlayType() MIME type check is case-insensitive, but Firefox's is case-sensitive, e.g. "video/mp4" vs "ViDeO/mP4".

2. Chrome and Safari's canPlayType() codec name check returns "probably" support for any "avc1.*" codec name (even "avc1.BOGUS"), but Firefox checks a short, case-sensitive list. Curiously, Chrome and Safari's codec name prefix check for "avc1." *is* case-sensitive.

See the attached test case.


* In bug 794171 comment 9, hsivonen says:

The RFC says the ISO BMF namespace is case-sensitive: http://tools.ietf.org/html/rfc6381#section-3.3

The canPlayType() spec doesn’t say anything to override the RFC: 
http://www.whatwg.org/specs/web-apps/current-work/#dom-navigator-canplaytype

That said, I wouldn’t oppose to making it ASCII case-insensitive if you file a WHATWG spec bug to request ASCII case-insensitivity and citing the outright wildcarding in WebKit.

Comment 1

[Chris Pearce [:cpearce (Not reading bugmail)]]

A test case:
http://flowplayer.blacktrash.org/fp5/canplay.html

Comment 2

[Chris Peterson [:cpeterson]]

cpearce: why would Firefox's canPlayType's case-sensitivity differ on Windows vs OS X? Does Firefox really use platform-specific code paths to parse these canPlayType strings?

To maximize compatibility, we should probably make canPlayType case-insensitive like Chrome, Edge/IE, and Firefox on OS X. OTOH, Safari is case-sensitive here and we have gotten away with it on Windows for years, so we could probably make Firefox on OS X case-sensitive, too.

It looks like Chrome's canPlayType results may have changed post-Blink. Chrome now matches Firefox on OS X.

Is container string case-sensitive, e.g. "video/mp4" vs "ViDeO/mP4"?

* Firefox on OS X: NO
* Firefox on Windows: YES?!
* Chrome on OS X and Windows: NO
* Safari: YES!
* Edge/IE: NO

Is codec string case-sensitive, e.g. "avc1.42E01E" vs "AvC1.42e01e"?

* Firefox on OS X: YES
* Firefox on Windows: YES
* Chrome on OS X and Windows: YES
* Safari: PARTIALLY? Returns "maybe" for "AvC1.42e01e" instead of ""
* Edge/IE: NO, codec string appears to be ignored.

https://bug800600.bmoattachments.org/attachment.cgi?id=670576

Comment 3

[Masatoshi Kimura [:emk]]

Mime types/subtypes are case-sensitive and parameter values are case-insensitive per RFC 2045.
https://tools.ietf.org/html/rfc2045#section-2
>   All numeric and octet values are given in decimal notation in this
>   set of documents. All media type values, subtype values, and
>   parameter names as defined are case-insensitive.  However, parameter
>   values are case-sensitive unless otherwise specified for the specific
>   parameter.

Comment 4

[Masatoshi Kimura [:emk]]

> Mime types/subtypes are case-sensitive and parameter values are case-insensitive per RFC 2045.

Sorry, it was opposite.
Mime types/subtypes are case-insensitive and parameter values are case-sensitive per RFC 2045.

Comment 5

[Chris Peterson [:cpeterson]]

jya's fix for bug 1230353 fixed this bug in 45. The following expression now returns true on OS X, Windows XP, and Windows 10:

document.createElement("video").canPlayType("video/mp4") === document.createElement("video").canPlayType("ViDeO/mP4")